Explosive composition comprising ammonium nitrate, decaborane, and a hydrocarbon oil



United States Patent EXPLQSIVE COMPGSITION COMPRISING AMMO- This invention relates to improved ammonium nitrate explosive compositions and, more particularly, it relates to to ammonium nitrate explosive compositions containing decaborane or yellow solid.

One of the objects of the present invention is to provide ammonium nitrate explosive compositions which can be safely handled in transport with little danger of shock initiation and which can be detonated effectively by means of an electric blasting cap. Another object of this invention is to provide ammonium nitrate explosive cornpositions which produces a detonation of useful magnitude and force upon proper initiation. Another object of this invention to provide ammonium nitrate explosive compositions containing decaborane or yellow solid. Another object of the invention is to provide ammonium nitrate explosive compositions of greatly increased power.

It is known in the art to prepare decaborane. The material is a stable, white crystalline solid which melts at 99.5 C. and which boils at 213 C. Decaborane is a boron hydride of very high boron content and has a very high heat of combustion.

The pyrolysis of diborane to form higher boron hydrides is well known. The operation can be carried out, for example, at a pressure within the range from to 0 to 100 p.s.i.g., at a temperature within the range from 150 C. to 300 C. and with a residence time in the pyrolysis zone of from about 1 second to 6 seconds. The diborane pyrolyzed can be in admixture with diluent hydrogen introduced into the pyrolysis zone along with the diborane, the amount of diluent hydrogen being from about 25 to 95 percent by weight, based upon the weight of the diborane'. The pyrolysis of the diborane results in the production of tetraborane, pentaborane-9, pentaborane-l 1, decaborane and so forth. Note, for example, the article by McCarty and Di Giorgio appearing on pages 3138 to 3143 of the July 1951 issue of the I ournal of the American Chemical Society.

Frequently, in diborane pyrolysis a yellow solid is formed in addition to the aforementioned boron hydrides. This solid is a mixture of polymerized higher boron hydrides higher than decaborane. The solid can be separated from the decaborane with the aid of kerosene, decaborane being more soluble in kerosene than the yellow solid. This is described, for example, in Zaslowsky and Madaus application Serial No. 560,113, filed January 19, 1956, now US. Patent 2,983,590. The yellow solid is, in general, chemically inert and resists efforts to convert it into readily useable chemical compounds. Sometimes,

over 50 percent of the end product of the diborane pyrolysis consists of the yellow solid.

The novel compositions of this invention can be prepared with fertilizer grade as well as with explosive grade ammonium nitrate. Generally, fertilizer grade ammonium nitrate contains various additives or fine particulate coat Ffce ings added to inhibit caking and to promote free flowing characteristics of the material. Ammonium nitrate, as referred to herein, is defined as ammonium nitrate containing up to 3 percent of various additives such as clay, wax, diatomaceous earth, chalk, etc. in addition to a moisture content ranging up to about 2 percent. Either the granular or prilled form of the ammonium nitrate is useful in preparing the novel explosive compositions of this invention.

The novel compositions of this invention can be prepared in a variety of ways-such as by first admixing the ammonium nitrate and a hydrocarbon oil and then admixing with the oiled ammonium nitrate the required amount of particulate decaborane or yellow solid. If desired, the hydrocarbon oil, such as crude oil, fuel oil, etc. dissolved in pentane, hexane or any other suitable solvent can be added to the ammonium nitrate with mixing and the solvent can then be removed under vacuum. The explosive compositions of this invention have both liquid and solid phases.

Suitable hydrocarbon oils are those which are liquid at room temperature and pressure. Useful hydrocarbon oils include crude oil, fuel oil, lubricating oil fractions and mixtures thereof, kerosene, etc.

In preparing the compositions of this invention granular ammonium nitrate having a particle size of from about 8 to about 200 mesh can be utilized. The sensitivity of the explosive composition is increased by the use of the smaller mesh sizes. Ammonium nitrate prills having a diameter of from about 0.093 inch to about 0.009 inch are also satisfactory for use in preparing the novel explosive compositions. In a like manner the particle size of the decaborane and yellow solid suitable for use in the compositions of this invention can be from about 8 to about 200 mesh.

The novel explosive compositions of this invention will contain from about to about percent by weight of particulate ammonium nitrate, from about 0.2 to 22 percent by weight of particulate decaborane or yellow solid and from about 1 to about 10 percent by weight of a hydrocarbon oil.

The explosive compositions of this invention can be charged directly into a borehole and detonated by means of an electric blasting cap. If desired, these novel compositions can be packaged in a shell of waterproof material such as plastic film, paper treated with paraflin or other waterproofing materials, or in metal cans.

Detonation of the explosive compositions of this invention can be accomplished in a conventional manner through the use of electric blasting caps. Actual detonation tests conducted in the field showed that the novel explosive compositions are substantially more powerful than conventional ammonium nitrate-hydrocarbon oil explosives when tested under the same conditions.

The following examples serve to illustrate specific embodiments of this invention and are not limitative.

EXAMPLE I b percent through 100 mesh) was admixed with the kerosene-containing ammonium nitrate composition to yield 200 grams of the explosive composition containing 5.0 percent kerosene by weight and 0.5 percent yellow solid by weight.

To demonstrate the explosive power of the explosive composition prepared in this example it was detonated in the field. Detonation was achieved by means of an engineer special blasting cap. The charge as tested was packaged in a cylindrical paper container having a diameter of about 2.5 inches. The. container with the charge was placed in a suitable hole in such a manner that the top of the charge in the container was flush with the ground. After the blasting cap had been placed in the explosive charge through the open top of the container, lead wires from the cap were connected to a firing control switch and the composition was detonated by closing the switch. The magnitude of the resulting detonation was determined by measuring the size of the crater produced.

lar ammonium nitrate (particle sizel00 percent through mesh) as well as ammonium nitrate prills having an average diameter of from 0.060 to 0.070 inch) was used. Decaborane of the same particle size as that used in Example III was employed in these examples. The compositions prepared and the results of firing tests conducted with these materials are also recorded in Table 1.

EXAMPLES VII-X Table 1 FIELD TESTING OF AMMONIUM NITRATE EXPLOSIVE COMPOSITIONS CONTAINING DECABORANE OR YELLOW SOLID Explosive compositions Weight Yellow Deea- Ammo- Example (grams) solid borane nium Kerosene Detonator (cubic (percent (percent nitrate (percent inches) by by (percent by weight) weight) by weight) weight) I 200 0. 5 0. 0 1 94. 5 5. 0 Engineer 710 special blasting cap. 200 0. 5 0. 0 1 94. 5 5. 0 (l 705 192 0. 0 0. 5 2 94. 5 5. 0 649 192 0. 0 0.5 2 94. 5 5. 0 584 200 0. 0 0.5 1 04. 5 5. 0 931 200 0. 0 0. 5 1 94. 5 5. 0 625 193 0. 0 0. 0 2 94-. 5 5. 5 191 193 0.0 0. 0 2 95.0 5. 0 303 200 0. 0 0. 0 1 94. 5 5. 5 570 200 0.0 0. 0 1 94. 5 5. 5 511 1 Prilled ammonium nitrate-Average diameter, 0.060 to 0.070 inch. 2 Granular ammonium nitratePartiele size, 100 percent through 40 mesh.

Although it is true that the crater size alone is not indicative of the amount of earth formation that is broken up, it does give an indication of the work potential of the mixture detonated. The result of the firing test is given in Table 1.

EXAMPLE II A second explosive composition containing 5.0 percent by weight of kerosene, 1.0 percent by weight of yellow solid and the balance ammonium nitrate was prepared in the same manner as described in Example I. The result of the firing test conducted withthis explosive composition is given in Table 1.

EXAMPLE III EXAMPLES IV-VI Three additional explosive compositions containing ammonium nitrate, kerosene, and decaborane were prepared in the same manner as described in Example III. Granu- EXAMPLES XI-XXI A number of additional ammonium nitrate explosive compositions containing a liquid hydrocarbon and decaborane or yellow solid were prepared and tested for impact sensitivity. It was demonstrated by these tests that the novel explosive compositions of this invention have a low degree of sensitivity.

A one to two gram sample of each particular explosive composition was prepared. The particle size of the ammonium nitrate, decaborane and yellow solid employed in preparing the explosive compositions of Examples XI- XXI was the same as that utilized in the previous examples. The hydrocarbon oil utilized was a medium viscosity vacuum pump oil. These compositions were prepared by first admixing the hydrocarbon oil in the form of a 25 percent solution of the oil in pentane with granular ammonium nitrate and then removing the solvent under vacuum. To the oiled ammonium nitrate there was then added with mixing yellow solid or decaborane.

The impact sensitivity determinations reported in Table 2 which follows were conducted using a drop weight tester. The material to be tested was placed in a sample cup and covered with a thin (0.011 inch) stainless steel disc. This was done to prevent actual contact between the sample and the hammer thus eliminating cleaning the hammer after each impact. The sample was placed in the tester, the weight was dropped from a measured height, and the effect of impact noted. The weight was raised or lowered to determine the height at which explosion occurred in three out of six samples tested. The compositions pre- 6 pared and the results of the impact sensitivity tests are reto 100 percent of the said particulate ammonium nitrate ported in Table 2 which follows: is of fertilizer grade.

Table 2 IMPACT SENSITIVITY OF AMMONIUM NITRA'IE EXPLOSIVES CONTAINING A HYDROGARBOb OIL AND DECABORANE OR YELLOW SOLID Explosive composition Impact producing Ammo- Deca- Yellow Hydro- Sample Weight Height detona- Example number nium borane solid carbon weight dropped dropped tion nitrate (percent (percent oil 1 (grams) (pounds) (inches 1 (inch- (percent y by (percent pounds) by weight) weight) by Vt eight) weight) l 15 i 360. 0o 94. 4 4. 60 050 19 24 00 456. 00 94. 5 5. G0 050 93. 4 0. 10 050 7 0 12. 32 86 24 93. 3 0. 20 050 7 0 11. 78 82 46 94. 1 2. 00 858 1'6 0 10. 212 94. 3 3. 70 5 0 i 15 i 00 i 360. 00 94. 4 4. 6O 050 19 24. 00 456. 00

1 Medium viscosity vacuum pump 011.

References Cited in the file of this patent What is claiaed UNITED STATES PATENTS 1. An explosive composition consisting essentially of from about 70 to about percent by weight of particu- 39 2,894,830 Nerad et July late ammonium nitrate, from about 0.2 to about 22 pergterllgel 32 i cent by weight of a particulate decarborane, and from 3046888 8 3: y e a 3 1962 ilialout 1 to about 10 percent by weight of a hydrocarbon 3,066; Ramysden Nov. 27 1962 2. The explosive composition of claim 1 wherein the 35 OTHER REFERENCES particle size of the said particulate ammonium nitrate M C et 1; J, A Ch S l, 73, July 1951, and of the said particulate boron compound is from 3138-3143,

about 8 to about 200 mesh. Martin: Journal of Chemical Education, vol. 36, No. 5,

3. The explosive composition of claim 1 wherein up May 1959, pp. 208214. 

1. AN EXPLOSIVE COMPOSITION CONSISTING ESSENTIALLY OF FROM ABOUT 70 TO ABOUT 95 PERCENT BY WEIGHT OF PARTICULATE AMMONIUM NITRATE, FROM ABOUT 0.2 TO ABOUT 22 PERCENT BY WEIGHT OF A PARTICULTE DECARBONANE, AND FROM ABOUT 1 TO ABOUT 10 PERCENT BY WEIGHT OF A HYDROCARBON OIL. 